Orthodontics is a specialty in dentistry that moves teeth within the jaw bone and straightens the teeth by moving them to the proper three-dimensional location. In orthodontics, brackets are pieces of metal with a slot that accepts a flexible or rigid metallic wire. Such brackets are conventionally bonded to the teeth on a base and serve as vehicles allowing the orthodontist to apply force to the tooth to move it across the wire to its proper location with the proper angulation.
The interaction of force, wires and brackets guides the three dimensional movement of the tooth. The force applied to the teeth, by the wire, forces the teeth to slowly alter their positions to align with the wire and therefore positioned correctly in three dimensions.
Conventional brackets have a fixed slot wherein the position of the slot relative to the tooth is fixed. Historically, brackets were the same for all teeth, regardless of patient individuality. Since every tooth has a unique three dimensional relationship with the rest of the teeth, the orthodontist was required to bend the wire that passed across the bracket slot in order to correct tooth angulation for each individual tooth.
In orthodontics, the angulation of the bracket slot in each dimension is described differently. The angulation of the bracket slot in the left-right direction is called ‘tip’ and the angulation of slot in the back-forward direction is called ‘torque’. Each and every tooth, in a normal position, has a certain tip and torque. A modification was presented a few decades ago by which specific brackets were created for every tooth according to their average angulations so that when a straight wire was passed through the slot, the difference between the angle of the straight wire and the angle of the slot would force the tooth to track the wire and achieve the proper average angulation. However, the inaccuracies occurred when a bracket was not bonded to the proper location on the tooth, which led to an improper angulation of the tooth and ultimately a misaligned tooth.
Also, the presumed angulations are merely averages, based on estimates of average sizes and shapes of teeth. Each individual is different with varying morphology for their teeth. Whenever a patient's teeth do not fall within the normal range, the straight wire technique does not produce optimum tooth angulation and location. Commonly brackets are not always placed in the proper location on the tooth resulting in erroneous bracket positioning. In order to correct for such problems, a certain number of brackets are repositioned during the course of the treatment to address these inaccuracies and improper bracket placements. Repositioning is both time-consuming and expensive and oftentimes does not cure the improperly positioned bracket. The process of bracket repositioning involves a patient's office visit, removal of the old bracket, polishing the tooth surface, priming the surface and applying the new bracket to the surface. This process can take anything from 5 to 15 minutes per tooth, depending on the location of the bracket and the experience of the assistant.
A dynamic base for the bracket addresses these deficiencies by allowing the orthodontist to manually adjust the relationship of the slot with the base during the course of treatment. Recently, systems have been developed that incorporate movable brackets, however those systems have complicated designs and would be difficult to use in the practice of orthodontics.
In modern orthodontics, proper bracket placement determines the quality of orthodontic treatment as the practitioners have moved from bending wires to using brackets with pre-determined angulations of the slot relative to the bracket base. There are clear guidelines on how to place brackets accurately, so that with a straight wire that is not bent, the teeth will be automatically guided to their proper angulations.
With introduction of the dynamic bracket system, the need for repositioning brackets due to erroneous positioning will be eliminated. This change will lead to lower treatment cost by decreasing the amount of time the patient spends at the clinic (less time away from work or school) and decreasing patient treatment time chair side. In addition, the quality of care delivered to the patient from the orthodontist is greatly improved.